Liquid level control device



mm nUU Nov. 3, 1936. J. SWINB'URNE 2,059,716

LIQUID LEVEL CONTROL D EV,`ICE

Filed Feb. 2, 1934 INVENTOR James Swmburne BY ,QW 91;/

ATTORNEY v Patented Nov. 3, 1936 UNITED STATES @con bis mmm PATENT OFFICE LIQUID LEVEL CONTROL DEVICE James Swinburne, East Orange, N. J., assignor to Carrier Engineering Corporation, Newark, N. J., a corporation of New York Application February 2, 1934, Serial No. 709,541

8 Claims. (Cl. 137-68) This invention relates to the method of and means for controlling the level of liquids within an open sump, or well, and more particularly, to the control of the flow of a liquid from a closed tank to an open sump.

It is an object of this invention to supply a liquid from a closed reservoir to an open sump for the purpose of replacing such quantities of liquid as are lost from the sump from any cause.

Another object of the invention is to provide a gravity feed from a sealed reservoir to an open sump and to control the flow of liquid in accordance with losses from the sump.

It is a further object of this invention to provide a means for lling said reservoir from a remote point.

The invention has as another of its objects the provision of means for stopping, or limiting, the ow of liquid from the reservoir to the sump whenever the reservoir is being filled.

A feature of the invention resides in the provision of a liquid passage between the sump and the bottom of the reservoir, and an air, or vapor, passage between the top of the reservoir and the maximum liquid level in the sump.

Another feature of the invention resides in the provision of an inverted trap in the liquid passage, and means for introducing air, or vapor, into the top of said trap whenever the reservoir is being filled.

Still another feature resides in the provision of a liquid passage between the reservoir and the sump, of much smaller capacity than the passage constituting the lling means for said reservoir.

A further feature of the invention resides in the provision of a trap in the iilling means for the reservoir, which trap constitutes a liquid seal to prevent the admission of air to the reservoir.

Other objects and features of the invention, as well as those enumerated, will be more apparent from the following description, to be read in connection with the accompanying drawing, in which:

Fig. 1 is an elevational View, partly in section, of one form of the invention,

Fig. 2 is an elevational View, partly in section, of a modification of the invention shown in Fig. 1, and

Fig. 3 is an elevational view of a part of Fig. 2, a portion of the casing being broken away to show the interior thereof.

While the invention may be utilized for a number of purposes, it is herein shown and described in connection with the refrigeration equipment of an air conditioning system for a railway car. Thus, in the drawing, similar designations referring to similar parts, numeral 5 indicates a casing mounted beneath the floor 6 of a conventional railroad car (not shown). The casing 5 may contain an entire refrigeration apparatus, including an evaporator, compressor and a condenser as is shown in copending application, Serial No. 700,670. In this application, only that part of the casing in which is contained a condenser 1 and a sump, or well 8, located therebeneath, is shown. For the purpose of liquefying the hot vapors supplied to condenser 'I through passageway 9, applicant utilizes the principles of evaporative cooling. To this end, water is withdrawn from sump 8 through pipe Ill, and is discharged by a suitable pump (not shown), through spray header II, over the surfaces of the condenser. Any excess, of course, falls back into the sump and is recirculated. Air flowing in the direction indicated by arrows I2 contacts the wet condenser surfaces, absorbs a part oi the water, and consequently tends to cool the condenser to a temperature corresponding to the wet bulb temperature of the incoming air.

It is apparent that' some of the water from sump 8 is constantly being lost through this evaporative process. To compensate, at least partially, for this loss, applicant provides a sealed reservoir I3 from which water can flow, by gravity, through pipe III (Fig. 1) into siunp 8. Since the refrigeration apparatus is not always in operation, and since the rate of evaporation from the condenser surfaces varies, it is apparent that some means must be provided to control the flow. To this end, applicant provides a passageway I5, one of the ends of which terminates within reservoir I3 proximate the top thereof, and the other end at the point at which it is desired to maintain the liquid level in sump 8. In operation, air (through passageway I5) is admitted to the top of reservoir I3 to displace the water which flows through pipe I4 into the sump 8. When the sump is filled to a desired point, the liquid seals the end of passageway I5, thus eiectively preventing the further admission of air into the reservoir. Thereafter, of course, atmospheric pressure balances the head of liquid and thereby prevents further flow through pipe I4. Whenever the level in sump 8 drops below this maximum point, the end of passageway I5 is uncovered, air is admitted to reservoir T3, and a ow of water through pipe I 4 is again established. Thus, applicant provides a simple control which is completely automatic, and which is inherently free from any possible mechanical diiiculty.

It is apparent that the whole success of the flow control depends upon eiectively sealing the reservoir, and it is equally apparent that the tank will, from time to time require refilling. While a cap seal, or other similar device could be used, such devices are subject to wear and tear, and further, their efficiency is dependent upon some human agency. Applicant avoids these inherent frailties by utilizing a liquid seal.

Thus, a U shaped trap I6 has one leg Ia joining the bottom of reservoir I3 and its other leg I6b joining a funnel I'I. As can be seen, the leg I 6b rises above the top of reservoir I3. Therefore, a column of liquid will stand in leg Ib to a height corresponding to the level o-f liquid in the reservoir, and so long as there is any water in the reservoir, this column will effectively prevent the ingress of air.

In the practical adaptation described, that is, the application of the invention to a railroad car, the reservoir is beneath the car oor in a most inaccessible place. However, by extending leg ISC of the trap, the iilling funnel II may be placed at any convenient point, for eX- ample, at the side of the car.

In connection with Fig. l, it is apparent that whenever the reservo-ir is being filled, the head of liquid in the reservoir is being increased without displacing a corresponding volume of air. Therefore, during the lling period, there will be a constant flow of water from the reservoir into the well 8. To restrict this wastage to a minimum, applicant makes pipe I4 of much smaller capacity than is the trap I6. Hence, during the lling operation, water is discharged intol the reservoir at a rate which greatly exceeds the rate at which it can ow out. The resulting air pressure automatically relieves itself through passageway I5.

Fig. 2 shows a modification of the invention in which is included a means for preventing the flow of liquid from reservoir I3 toI trough 8 whenever the reservoir is being filled. To this end, applicant provides a siphon, or inverted trap, I8 in the liquid line I4. A passageway I9, as illustrated, joins reservoir I3 at point 22, (below the top of Siphon I8) passes downwardly, then upwardly to a point 20 at which point the passageway is enlarged, and thence downwardly into the top of siphon I8.

In operation, assuming that the system is empty, water may be introduced into the reservoir through trap I6, and the reservoir may be filled to a point corresponding to the height of siphon I8 without causing any liquid to flow into trough 8. When the liquid level in the reservoir rises above point 22, some water will pass into passageway I9, and will be held in the trap formed in the lower part thereof. As the liquid level rises above the top of the siphon, it is apparent that some air will be trapped in the upper part of passageway I9. Simultaneously, of course, siphon I8 will be lled, and a ow of liquid from the reservoir to the trough will be established. When the trough is filled to a desired point, the liquid therein will seal the end of passageway I5, and the flow through the trap will cease. If the liquid level in the trough decreases, passageway I5 will again be uncovered and a ow of liquid through the Siphon will again be established. In other words, the operation of the device of Fig. 2 to maintain the level in the trough 8 at a desired point is precisely the same as the operation of the device of Fig. 1.

The negative pressure, or vacuum, at the top of Siphon I8, so long as the Siphon is lled, is always B plus C inches of water, while the negative pressure, or vacuum, in the reservoir I3 varies between a maximum vacuum of B plus C inches of water and a minimum vacuum of C inches of water. Therefore, as the liquid level in the reservoir decreases, the vacuum in the reservoir decreases, or more precisely, the pressure in the reservoir increases. Consequently, the liquid in tube I9 rises, and when the level in the reservoir falls to a desired minimum, the column of liquid in passageway I9 stands to a height of B inches. Hence, the eiective height A of passageway I9 is made equal to, or very slightly greater than, the effective height B of the Siphon I8. Assuming that water is now introduced into the reservoir through trap I6, it is apparent that the pressure therein will rise. This pressure will force the liquid in I9, and consequently, the air contained therein, into the top of the siphon I8. Instantly, the siphon is broken, and necessarily, any possible flow from the reservoir tothe trough is terminated. Hence, the reservoir may be relled without aiectng the trough; and the operation in entrapping air in I9, and completing the siphon will be exactly as was described above.

Under ordinary circumstances, the water velocity through trap I 8 is very small. However, when the trough 8 is completely empty, the ow through I8 must continue for some time. During this period, it is possible that a fairly high water velocity will be attained. In order to prevent this moving liquid from entraining, and thereby removing the air trapped in passageway I9, applicant provides a lip 2| (Fig. 3) for directing the liquid flo-wing through the siphon against the end of the passageway.

Since certain changes in the process and illustrative embodiments of the invention may be made without departing from its scope, it is intended that all matter contained in the above description, or shown in the accompanying drawing, shall be interrupted as illustrative, and not in a limiting sense.

I claim:

1. The method of controlling the level of liquid in an open sump which comprises siphoning liquid from a closed reservoir into an open sump, causing the liquid in the open sump to seal said reservoir when the level therein rises to a desired point, and introducing air from said reservoir into the siphon in response to changes in air pressure in said reservoir whenever liquid is introduced into said closed reservoir.

2. A combination of apparatus of the character described, comprising a sealed reservoir, an open sump located below said reservoir, a liquid passageway from said reservoir to said sump, a siphon in said liquid passageway, and a passage between said reservoir and the top of said siphon, said passage constituting an air trap.

3. In an apparatus for controlling the liquid level in an open sump, a sealed reservoir, an open sump, a siphon between said reservoir and said sump, a passageway between said reservoir and the top of said siphon, said passageway constituting an air trap, and an air passageway between said reservoir and the point of desired liquid level in said sump.

4. In a combination of apparatus of the character described, including a sealed reservoir, an

open sump, a siphon between said reservoir and sump, a passageway between said reservoir and the top of said siphon, said passageway, providing an air trap, and an air passageway between said reservoir and the point of desired liquid level in said sump, a filling means for said reservoir and a liquid trap in said filling means for preventing admission of air to said reservoir through said filling means.

5. In a combination of apparatus of the character described comprising a sealed reservoir, an open sump, a siphon between said reservoir and said sump, and a passageway joining said reservoir and the top of said Siphon, said passageway constituting an air trap, the vertical height of said air trap being slightly greater than the effective height of said Siphon.

6. In an apparatus for controlling the liquid level in a sump, a sealed reservoir, an open sump, a siphon between said reservoir and said sump, an air passageway between said reservoir and the UUUI UII point of desired liquid level in said sump, and means for breaking the Siphon responsive to changes in air pressure within the reservoir.

7. In an apparatus for controlling the liquid level in a sump, a sealed reservoir, an open sump, a siphon between said reservoir and said sump, an air passageway between said reservoir and the point of desired liquid level in said sump, and means for breaking the siphon responsive to changes in the level of liquid within the reservoir.

8. In an apparatus of the character described for controlling the liquid level in an open sump, a sealed reservoir, an open sump, a siphon providing communication between said reservoir and said sump, a passageway providing communication between said reservoir and a point in said sphon, said point being between said reservoir and said sump, said passageway constituting an air trap.

JAMES SWINBURNE.

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